1. Field of the Invention
The present invention relates to an electronic device to which an electronic package, including, for example, a printed circuit board, can be removably mounted.
2. Description of the Related Art
An electronic device such as a personal computer or the like permits the user to mount or replace an electronic package such as a printed circuit board or the like, so that the system can be expanded or modified. Therefore, the case of the electronic device is provided with an insertion port for inserting the electronic package in the case. Furthermore, a power input cord can be connected to the electronic device. The power input cord has a plug which can be plugged into a power input inlet provided in the case.
The electronic package may be broken if it is removed from or mounted to the device while the power input cord is connected to the electronic device and the power switch of the electronic device is turned on. Therefore the power switch of the electronic device must be turned off before removing or mounting the electronic package. The user's manual of the electronic device should contain a warning that the power source must be turned off when the electronic package is to be removed or mounted. However, the user may carelessly remove or mount the electronic package while the power source is turned on.
Therefore, it is desired to employ a constitution which does not permit the electronic package to be removed or mounted unless the power cord is disconnected from the electronic device, in order that the electronic package will not be damaged even if the user removes the electronic package with the power switch being turned on.
Japanese Unexamined Patent Publication (Kokai) No. 61-61496 discloses an interlocking mechanism which does not permit the electronic package to be removed from or mounted to the electronic device if the power cord is connected to the electronic device. This interlocking mechanism includes a bell crank that is moved by a plug connected to the power cord.
When the plug is not fitted to the power input inlet, the bell crank is at a rest position and is not engaged with the electronic package, permitting the electronic package to be mounted on, or removed from, the electronic device. When the plug is fitted to the power input inlet, the bell crank is brought into an operative position. At the operative position, the bell crank protrudes into the case through an opening in the side wall of the case of the electronic device, and receives an end of the electronic package when it is inserted in the electronic device, to prevent electronic package from being coupled to a related electronic part (e.g., connector) in the electronic device.
The interlocking mechanism also includes a locking rod arranged in the electronic package. The electronic package has a rectangular parallelepiped shape having longest sides, next longest sides and shortest sides, in which the longest sides are arranged in a horizontal direction of the electronic device, the next longest sides are arranged in a vertical direction of the electronic device, and the shortest sides are arranged in the direction of depth of the electronic device. Therefore, the package-accommodating portion of the electronic device is a wide and shallow cavity. The locking rod is arranged in parallel with the longest side of the electronic package, i.e., arranged in the horizontal direction in parallel with the surface of the electronic device.
The opening in the side wall of the case of the electronic package and the opening in the side wall of the electronic device are coaxially arranged on the axis of the locking rod. In the state where the electronic package is disposed at a predetermined position in the electronic device and the plug of the power cord is fitted in the power input inlet, the bell crank passes through the opening in the side wall of the case of the electronic device and pushes the locking rod, so that the locking rod enters the opening in the side wall of the case of the electronic package on the side opposite to the bell crank and into the opening in the side wall of the electronic device, whereby the electronic package is locked in the case of the electronic device. When the plug is removed from the power input inlet, the bell crank moves to the rest position, so that the locking rod is retracted into the electronic package under the bias of a spring, whereby the locking is released permitting the electronic package to be taken out from the electronic device.
In the above-mentioned conventional interlocking mechanism, the bell crank is located in the casing of the electronic device and cannot be clearly seen by the operator. Therefore, the user who does not know that the bell crank is at the operative position may try to forcibly insert the electronic package in the electronic device, causing the electronic package to be damaged. Also, the plug moves the bell crank relying upon the cam action, and a large force is required for inserting the plug. Besides, since the locking rod is arranged inside the electronic package, it is not possible to use a conventional electronic package without such a locking rod. Moreover, a limitation is imposed on the direction for inserting the electronic package.